Method for locating an underground cable

ABSTRACT

There is disclosed an assemblage for laying an underground cable. This assemblage includes a movable but stationarily operated power plant, a digging tool and a cable laying tool. The digging tool and the cable laying tool are connected to the power plant so that they can be extended from the power plant to a selected distance and are then pulled back to the power plant. While being so pulled back the digging tool digs a trench and the cable laying tool feeds cable to be laid into the trench as the same is being formed. A brake is mounted on the cable laying tool and co-acts with the same so as to avoid slack in the cable while the same is being laid.

0 United States Patent 1 1111 3,886,755

Lundin June 3, 1975 [54] METHOD FOR LOCATING AN 3,497,016 2/1970 Ryan61/726 X 9 3,726,099 4/1973 Ruge 75 :JNDERGRgliND Z L d E k d 3,747,3577/l973 Erickson et al 6l/72.6 355; H e FOREIGN PATENTS OR APPLICATIONS4l0,900 5 1934 U 't d K' d 61 72.6 [73] Assignee: Telefonaktiebolaget LM Ericsson, m e mg 0m Stockholm Sweden Primary ExaminerJacob Shapiro 22Filed; June 1973 Attorney, Agent, or Firm-Harte, Baxley & Spiecens [21]Appl. No.: 367,425 [57] ABSTRACT There is disclosed an assemblage forlaying an under- [30] Foreign Application Priority Data ground cable.This assemblage includes a movable but June 21, 1972 Sweden 8164/72stationarily Operated power p a gg g tool and a Feb. 20, 1972 Sweden .123400 72 cable y g tool. The digging tool and the cable laying tool areconnected to the power plant so that they can [52] U5. C1. 61/72.6;37/193; 172/700 be nded from the power plant to a selected dis- [51]Int, Cl, A011 3/64; F161 1/00; A011 13/08 tance and are then pulled backto the power plant. [58] Field of Search 61 /72.6, 72.5, 72.7, 72.1,While eing so pulled back the digging tool digs a 6l/72.2; 37/193;172/700 trench and the cable laying tool feeds cable to be laid into thetrench as the same is being formed. A brake is [56] References Cit dmounted on the cable laying tool and co-acts with the UNITED STATESPATENTS same so as to avoid slack in the cable while the same 1,854,6174 1932 Maloon 61/726 ls bemg 3,406,525 10/1968 Kinnan 61/726 7 Claims, 8Drawing Figures Pmwanms mm 11886755 SHEET 1 FATE .TEB 3 SHEET aassflssMETHOD FOR LOCATING AN UNDERGROUND CABLE The present invention relatesto a method for locating an underground cable, consisting in opening atrack in the ground and to place the cable in the opened track and thento refill the track over the cable.

As cables which shall be located in the ground become cheaper all thetime and the working costs for the location increase. work is carriedout in several places with development of different machines for suchlocation. A great number of such machines have already been constructedand used to a great extent abroad. Machines have even been developed inSweden, and these are specially adapted to the ground conditions inSweden. The fastest and therefore cheapest method for cable locationseems to be direct location by means of a cable plough, which after oneor more drivings along the same distance locates the cable at thecorrect depth in the ground.

In practice, however, it has appeared that it is difficult even withvery expensive machines to plough in cables into wooded ground,especially coarse roots effectively stop the cable-laying.

One has earlier tried to use different equipment for cable ploughing,where in. very big machines of the caterpillar type with a non-vibratingplough have been used. Such equipment would probably be too expensiveand besides, it can only be used when the ground conditions are good,i.e. in arableand meadow ground. Even plough equipment with a four-wheeldriven tractor and with a vibrating plough has been used. The vi bratingplough increases the practicability in spite of the limited tractiveforce from the wheels, for which reason location can take place inrather stony ground since the plough several times has been drivenwithout cable. Even with this machine the practicability is limitedregarding wooded ground, where first and foremost coarse roots providehindrance. At practically all ploughing a hydraulic excavator isnecessary as a complement when forcing hindrance as larger ditches,roads, ground with roots and/or big stones and so on.

Up to now known methods used when ploughing down cables have theadvantages that in suitable ground the expenses become low and theground damages get considerably less than with other methods. However,they have also some disadvantages, i.a. high expenses for the equipmentand bad exploitation of the equipment included in the plough andexcavator. Another essential disadvantage in earlier known machines isthat the cable, when the location process has started, only withdifficulty can be separated from the pulling machine and that thelocation only can be continued after manual excavation. If the ploughwith the cable layer which is fixed to the pulling machine is stopped byhindrance during the cable-laying, consequently quite time-wasting stepsmust be taken.

Furthermore, the previously known arrangements for ploughing down cablesare dependent on the evenness of the ground as the cable layer is wheelcarried. in consequence of which damages on the cable easily arise. ifthe driver can not operate the cable layer so that the movements of themachine over stones, roots and other unevennesses do not influence thecable.

Fromthe above mentioned it appears that there is a need of developingnew methods and machines for a faster and cheaper location ofundergroundcables. The

Cables should preferably be placed at requested depth without the needof a cable ditch beeing opened and then refilled after that the cablehas been drawn out. The intention with the present invention is toprovide such method and tools suitable for carrying out the method.

The invention will be described more in detail in connection with theenclosed drawings where diagramatically;

FIG. 1 shows the final stage during ploughing a track or a cable trench,

FIG. 2 shows the starting stage during location of a cable in an earlierploughed track,

FIG. 3-6 show different views of a location tool,

FIG. 7 shows a further embodiment of a location tool from the side andFIG. 8 shows the same tool from above.

In FIG. 1 is diagramatically shown an excavator (pulling vehicle) 10with a hinged digging arm 11, in the end of which remote from theexcavator a plough tool or a rasp or digger tool 12 is attached,furthermore, a location tool 13 and a piece of cable 14. The diggingmachine has two supporting legs 15 by means of which the excavatorstands steadily on the ground. The figure shows the final phase of aworking stage in which a track 16 has been loosened in the ground fromthe place where the location tool 13 is to the immediate proximity ofthe machine 10.

In FIG. 2 the machine 10 and the tool 13 are shown in the same positionas in FIG. 1 but the arm 11 has been extended so that it has beenpossible to stick in rasp 12 into a fastening means 131 on the upperpart of the tool 13 on the side turned towards the machine 10. Cable 14is passed through the tool 13 so that when tool 13 is drawn in theearlier loosened track 16 by the stationary machine 10 the cable 14 willbe gradually located in the bottom of thetrack. As the tool 13 is pulledtowards the machine 10 the track is refilled behind the tool and thecable 14 is thus located in the requested depth.

FIG. 3 shows the tool 13 from the side. It consists of two spacedplane-parallel walls 31 and 32, see also FIG. 4 which shows the toolfrom behind and FIG. 5 which shows the tool from above. These walls formtogether a unit similar to a plough in the forward direction andbackwards open and downwards closed with a strip 34 placed between thewalls 31 and 32 for steadily the unit and steering the passing cablethrough the tool. FIG. 6 shows a cut through the tool along the line AAin FIG. 3, with the oblique wall 34 for steering the inserted cable.

By means of a rasp 12, which in mounted position is bent towards theexcavator 10 and has an edge in the same direction it is quite easy toloosen the ground where the cable later will be placed. The shape of therasp 12 and the mobility and strength of the arm 11 and the fact thatthe excavator is not moved during the stage of loosening allow that allground which can be dug also can be rasped. Furthermore, big stones canbe broken and heavy roots torn off. During particularly difficultcircumstances the rasp can be brought to carry out a loosening workaround the stones and stubs in order to facilitate the finishing of atrack with loose substances.

Rasp 12 has a shape and thickness which suits to the fastening means 131on the location tool 13. The distance between sheets 31 and 32 in thistool corresponds to the diameter of the largest cable which is to belocated. When the tool 13 is pulled forward, the cable can gradually bepassed between the sheets 31 and 32 and be placed in the same depth inthe track in which the bottom of the tool is driven.

Summing up the location or laying of the cable takes place in the mannerthat the cable first is pulled out along the desired cable lengthwhereupon a track is loosened in steps of about two meters, i.e. as faras the movable arm of the pulling vehicle reaches, and the lo cationtool is then put down in the loosened track and pressed down by means ofthe arm to required depth. The cable is placed on the bottom and againstthe base wall of the location tool and as the tool gradually is moved inthe loosened track, the cable is gradually fed in and through thelocation too]. At the same time as loosening of a two meter distancetakes place in front of the location tool by means of the rasp the trackcan be refilled behind the location tool with a spade by the same personwho attends to the supplying of the cable.

In accordance with the description the location of a given cable lengthtakes places in steps of about two meters. It is of course possible thatfirst loosening of the whole cable length takes place and that the cablethereafter is located in the whole length without interruption. It is ofcourse also possible that the transportation of the rasp 12 respectivelylocation tool 13 takes place by means of a fixed arm or with aconnection 11 on the drawing vehicle which during the working stages ismoved along the cable length. Whether the one or the other method ischoosen depends on the ground conditions. As the rasp can be substitutedby a digging bucket there will be no need of an extra machine duringspecially difficult conditions.

Two plane-parallel walls 70 and 71 according to FIG.

7-8 spaced from each other provide a unit similar to a plough in theforward direction and opened on the backside and having a strip 72inserted between the walls for staying the tool and steering the cable14 passing through tool upon location of the cable.

At the plane-parallel walls there is attached a turnable drum holder 74one end 141 of which supports a rotatable drum 75 arranged for the cable14 which has to be located and the other end 142 of which is shaped as aguiding means for steering the cable 14 winded from the drum 75 togetherwith the strip 72. As appears from FIG. 7 end portion 142 is bent inabouth right angle to the other part of the drum holder and directeddown in about the same direction as the strip 72, so that the cable 14easily can be steered by the end portion by the strip 72 at the passagethrough the tool. In FIG. 7 is indicated that the lower part of the endportion 142 has a track, in which the cable 14 runs.

The drum holder 74 has two rectangular taps 143 for supporting in thecorresponding recesses in walls 70 and 71, and a through shaft 77 forsupporting two holders 160. The rectangular taps 142 and the recesses inthe walls have been shaped so that the drum holder can move enough inorder to obtain braking effect and free sliding respectively against abrake plate 76 which is attached to the holder 160. On the other hand,greater movements are prevented.

- The holders 160 of the brake plate 76 consist of two arms which arefixed outside of the walls 70 and 71 and seating on the through shaft 77on which the arms are maintained by a cotter or another suitablearrangement. The height of the brake plate 76 is regulated in proportionto the diameter of the cable drum 75 by means of a shaft 78, which hastwo lockable eccentrics against the walls and 71.

When the tool is standing still, the different parts take the positionswhich appear in FIG. 7, i.e. the drum rests against the brake plate 76due to the influence of the force of gravity. and hereby the cable 14 isprevented to be wound off from the drum, but when the tool is movedforward, (i.e. to the right in FIG. 7) pulling takes place in the cable14 in consequence of which the drum holder 74 is turned clockwise sothat the drum is lifted from the plate 76 and the cable can be wound upfrom the drum in accordance with the movement of the tool.

When locating an underground cable it is often desirable that aprotective strip of for example plastic is placed over the cable. Forthis purpose a roll 79 with plastic band 191 is arranged which isturnable between the two arms which hold the brake plate 76.

A strip guide 20 is attached to the walls 70 and 71 and guides theplastic band 191 from the roll 79 over the free part of the cable 14outside the tool.

We claim:

1. A method of laying an underground cable, said method comprising thesteps of:

providing a digging assembly including a movable but stationarilyoperating power plant, a digging tool. a cable laying tool and a pullingmechanism coupled at one end to the power plant and extendable to aselected distance. the extended end of the mechanism being attachable toeither tool;

moving the power plant to a location selected for laying an undergroundcable;

attaching the digging tool to the pulling means and extending the sameto a position at which the digging tool is at a selected distance fromthe power plant;

activating the power plant for pulling back the digging tool to effectloosening of the strip of ground along the withdrawal path of thedigging tool to prepare said ground for laying a corresponding length ofcable;

detaching the digging tool and attaching the cable laying tool and againextending the pulling means along the length of the strip of loosenedground; and

reactivating the power tool for pulling the cable laying tool back tothe power plant while simultaneously paying out cable from the cablelaying tool and placing the cable in space cleared by the cable layingtool in the ground by and while pulling back said cable laying tool.

2. An assemblage for laying an underground cable,

said assemblage comprising in combination:

a movable but staionarily operated power plant including a pulling meansextendable from a position adjacent to the power plant to a selectedextended position, said pulling means being retractable from theextended position to the adjacent position by activation of the powerplant;

a digging tool for loosening ground, said tool being attachable to theextended end of the pulling means for pulling the tool from the extendedposition to the adjacent position to effect loosening of the groundalong the path through which the tool is pulled back;

a cable laying tool attachable to said extended end of the pulling meansfor pulling said tool from the extended position to the adjacentposition, said cable laying tool including a space closed off by aploughshaped wall at the side facing the power plant when the cablelaying tool is attached to the pulling means and being open at the sideopposite to said plough-shaped wall. said plough-shaped wall displacingloosened ground as the cable laying tool is pulled back towards thepower plant. thereby providing a ditch for laying cable fed into thespace in the tool and fed out from the cable laying tool through theopen side thereof as said tool is being pulled back to the power plant;and

a cable drum for winding thereabout a length of cable to be fed intosaid space;

holder means supported by the cable laying tool, said holder meansincluding a pivotal two-arm lever, the fulcrum of the lever beingmounted on the cable laying tool. one arm of said lever mounting saiddrum;

the other arm of said lever guiding the cable; and

brake means also mounted on the cable laying tool, said brake meansincluding a bar pivotally mounted on said cable laying tool, and a brakemember mounted on said bar and disposed below said drum, said brakemeans being movable into and out of braking engagement with said cabledrum in response to pulling of the cable laying tool towards the powerplant;

said holder means being located and balanced so that the drum and thebrake means are biased by the gravitational force acting upon the druminto braking engagement when the cable laying tool is at a standstillbut are pivoted out of said braking engagement by the pull of the cableagainst said other lever arm overcoming the gravitational force when thecable laying tool is pulled towards the powers plant.

3. An assemblage according to claim 2, wherein said cable laying toolcomprises two spaced apart parallel walls, a base wall, and saidplough-shaped side wall adjacent to the base wall, said walls definingsaid space within the cable laying tool, and guide means for guidingcable fed into the space from the side thereof opposite to the base walland out of said space through the open side thereof.

4. The assemblage according to claim 2 and comprising a roll ofprotective strip material rotatably supported on said bar, and guidemeans guiding the strip material from said roll over cable emerging fromthe open side of said cable laying tool.

5. An assemblage for laying an underground cable, said assemblagecomprising in combination:

a movable but stationarily operated power plant including a pullingmeans extendable from a position adjacent to the power plant to aselected extended position, said pulling means being retractable fromthe extended position to the adjacent position by activation of thepower plant;

a digging tool for loosening ground. said tool being attachable to theextended end of the pulling means for pulling the tool from the extendedposition to the adjacent position to effect loosening of the groundalong the path through which the tool is pulled back:

a cable laying tool attachable to said extended end of the pulling meansfor pulling said tool from the extended position to the adjacentposition said cable laying tool including two spaced apart parallelwalls, a base wall, and a plough-shaped side wall adjacent to the basewall, said walls defining a closed space within the cable laying tool,said plough-shaped wall facing the power plant when the cable layingtool is attached to the pulling means and said space being open at theside opposite to said plough-shaped wall, said plough-shaped walldisplacing loosened ground as the cable laying tool is pulled backtowards the power plant, thereby providing a ditch for laying cable fedinto the space in the tool and fed out from the cable laying toolthrough the open side thereof as said tool is being pulled back to thepower plant;

guide means for guiding cable fed into said space from the side thereofopposite to the base wall and out of said space through the open sidethereof;

a cable drum for winding thereabout a length of cable to be fed intosaid space;

holder means supported by the cable laying tool, said holder meansincluding a pivotal two-arm lever, the fulcrum of said lever beingmounted on the cable laying tool, one arm of the lever mounting saiddrum; and

brake means also mounted on the cable laying tool and disposed belowsaid drum, said brake means including a bar pivotally mounted on saidcable laying tool, and a brake member mounted on said bar, said brakemeans being movable into and out of braking engagement with said cabledrum in response to pulling of the cable laying tool towards the powerplant, the other arm of said lever guiding the cable, said drum and saidholder means being located and balanced so that the drum and the brakemeans are biased by the gravitational force acting upon the drum intobraking engagement when the cable laying tool is at a standstill but arepivoted out of said braking engagement by the pull of the cable againstsaid other lever arm overcoming the gravitational force when the cablelaying tool is pulled towards the power plants.

6. An assemblage according to claim 5 wherein said guide means arecurved and positioned to guide cable to and along said base wall priorto leaving the space through the open side thereof.

7. The assemblage according to claim 5 and comprising a roll ofprotective strip material rotatably supported on said bar, and guidemeans guiding the strip material from said roll over cable emerging fromthe open side of said cable laying tool.

1. A method of laying an underground cable, said method comprising thesteps of: providing a digging assembly including a movable butstationarily operating power plant, a digging tool, a cable laying tooland a pulling mechanism coupled at one end to the power plant andextendable to a selected distance, the extended end of the mechanismbeing attachable to either tool; moving the power plant to a locationselected for laying an underground cable; attaching the digging tool tothe pulling means and extending the same to a position at which thedigging tool is at a selected distance from the power plant; activatingthe power plant for pulling back the digging tool to effect loosening ofthe strip of ground along the withdrawal path of the digging tool toprepare said ground for laying a corresponding length of cable;detaching the digging tool and attaching the cable laying tool and againextending the pulling means along the length of the strip of loosenedground; and reactivating the power tool for pulling the cable layingtool back to the power plant while simultaneously paying out cable fromthe cable laying tool and placing the cable in space cleared by thecable laying tool in the ground by and while pulling back said cablelaying tool.
 1. A method of laying an underground cable, said methodcomprising the steps of: providing a digging assembly including amovable but stationarily operating power plant, a digging tool, a cablelaying tool and a pulling mechanism coupled at one end to the powerplant and extendable to a selected distance, the extended end of themechanism being attachable to either tool; moving the power plant to alocation selected for laying an underground cable; attaching the diggingtool to the pulling means and extending the same to a position at whichthe digging tool is at a selected distance from the power plant;activating the power plant for pulling back the digging tool to effectloosening of the strip of ground along the withdrawal path of thedigging tool to prepare said ground for laying a corresponding length ofcable; detaching the digging tool and attaching the cable laying tooland again extending the pulling means along the length of the strip ofloosened ground; and reactivating the power tool for pulling the cablelaying tool back to the power plant while simultaneously paying outcable from the cable laying tool and placing the cable in space clearedby the cable laying tool in the ground by and while pulling back saidcable laying tool.
 2. An assemblage for laying an underground cable,said assemblage comprising in combination: a movable but staionarilyoperated power plant including a pulling means extendable from aposition adjacent to the power plant to a selected extended position,said pulling means being retractable from the extended position to theadjacent position by activation of the power plant; a digging tool forloosening ground, said tool being attachable to the extended end of thepulling means for pulling the tool from the extended position to theadjacent position to effect loosening of the ground along the paththrough which the tool is pulled back; a cable laying tool attachable tosaid extended end of the pulling means for pulling said tool from theextended position to the adjacent position, said cable laying toolincluding a space closed off by a plough-shaped wall at the side facingthe power plant when the cable laying tool is attached to the pullingmeans and being open at the side opposite to said plough-shaped wall,said plough-shaped wall displacing loosened ground as the cable layingtool is pulled back towards the power plant, thereby providing a ditchfor laying cable fed into the space in the tool and fed out from thecable laying tool through the open side thereof as said tool is beingpulled back to the power plant; and a cable drum for winding thereabouta length of cable to be fed into said space; holder means supported bythe cable laying tool, said holder means including a pivotal two-armlever, the fulcrum of the lever being mounted on the cable laying tool,one arm of said lever mounting said drum; the other arm of said leverguiding the cable; and brake means also mounted on the cable layingtool, said brake means including a bar pivotally mounted on said cablelaying tool, and a brake member mounted on said bar and disposed belowsaid drum, said brake means being movable into and out of brakingengagement witH said cable drum in response to pulling of the cablelaying tool towards the power plant; said holder means being located andbalanced so that the drum and the brake means are biased by thegravitational force acting upon the drum into braking engagement whenthe cable laying tool is at a standstill but are pivoted out of saidbraking engagement by the pull of the cable against said other lever armovercoming the gravitational force when the cable laying tool is pulledtowards the powers plant.
 3. An assemblage according to claim 2, whereinsaid cable laying tool comprises two spaced apart parallel walls, a basewall, and said plough-shaped side wall adjacent to the base wall, saidwalls defining said space within the cable laying tool, and guide meansfor guiding cable fed into the space from the side thereof opposite tothe base wall and out of said space through the open side thereof. 4.The assemblage according to claim 2 and comprising a roll of protectivestrip material rotatably supported on said bar, and guide means guidingthe strip material from said roll over cable emerging from the open sideof said cable laying tool.
 5. An assemblage for laying an undergroundcable, said assemblage comprising in combination: a movable butstationarily operated power plant including a pulling means extendablefrom a position adjacent to the power plant to a selected extendedposition, said pulling means being retractable from the extendedposition to the adjacent position by activation of the power plant; adigging tool for loosening ground, said tool being attachable to theextended end of the pulling means for pulling the tool from the extendedposition to the adjacent position to effect loosening of the groundalong the path through which the tool is pulled back; a cable layingtool attachable to said extended end of the pulling means for pullingsaid tool from the extended position to the adjacent position, saidcable laying tool including two spaced apart parallel walls, a basewall, and a plough-shaped side wall adjacent to the base wall, saidwalls defining a closed space within the cable laying tool, saidplough-shaped wall facing the power plant when the cable laying tool isattached to the pulling means and said space being open at the sideopposite to said plough-shaped wall, said plough-shaped wall displacingloosened ground as the cable laying tool is pulled back towards thepower plant, thereby providing a ditch for laying cable fed into thespace in the tool and fed out from the cable laying tool through theopen side thereof as said tool is being pulled back to the power plant;guide means for guiding cable fed into said space from the side thereofopposite to the base wall and out of said space through the open sidethereof; a cable drum for winding thereabout a length of cable to be fedinto said space; holder means supported by the cable laying tool, saidholder means including a pivotal two-arm lever, the fulcrum of saidlever being mounted on the cable laying tool, one arm of the levermounting said drum; and brake means also mounted on the cable layingtool and disposed below said drum, said brake means including a barpivotally mounted on said cable laying tool, and a brake member mountedon said bar, said brake means being movable into and out of brakingengagement with said cable drum in response to pulling of the cablelaying tool towards the power plant, the other arm of said lever guidingthe cable, said drum and said holder means being located and balanced sothat the drum and the brake means are biased by the gravitational forceacting upon the drum into braking engagement when the cable laying toolis at a standstill but are pivoted out of said braking engagement by thepull of the cable against said other lever arm overcoming thegravitational force when the cable laying tool is pulled towards thepower plants.
 6. An assemblage according to claim 5 wherein said guidemeans are curveD and positioned to guide cable to and along said basewall prior to leaving the space through the open side thereof.